Please help - Emission test badly failed - 88 90Q

[V. Jokic (via Sympatico)]

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I am new to the list... I failed (Ontario) emission test with my 88 90Q (5c=
yl, 10v), and the results were classified  (by the  testing  facility) as "=
extremely bad".

They even refused to work on it and  give me a "conditional pass" once I sp=
end $450 on the emission related repairs, since they said they knew nothing=
 about Audis... Ironically, local Audi dealer (nor any local shop specializ=
ed in European   imports), here in Niagara area, are not certified by the g=
overnment to do official  emission related repairs...

Since on a quattro  they can do only a two-speed idle test and measure only=
 CO and HC ppm, here are the results:

Idle (808 RPM):
CO% : allowed 1%,   measured 9.31%
HCppm: allowed 200,   measured 542

2500 RPM:
CO% : allowed 1%,   measured 4.52%
HCppm: allowed 200,   measured 232

Could anyone five me some idea what might be wrong?

Re CO, I suppose,  I should adjust the mixture, but I am unsure where the m=
ixture adjustment screw is located on an 88 90Q 5 cyl 10v engine (nor I hav=
e a Bentley manual...). Could someone give me dome hint?

Re HC, I am even unsure where to start from - perhaps oxygen sensor?

Also, does someone know what  the exact purpose of that screw on the top of=
 throttle (that works as the throttle stop) is? Can it have any influence o=
n the CO and/or HC  content? I did play with it  one time in the past, and =
managed to improve idle stabilization process, at that time, when a  the th=
rottle would be released, the RPM would dip down to 400 and then bounce bac=
k to about 800, but after turning that throttle stop screw anti-clockwise, =
the RPM now  quickly drops to about 1200 and then usually goes slowly down =
to 800.

Any help would be greatly appreciated.

Regards,

Joe

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